Chemical modification of various surfaces has been the subject of intensive research. Examples of such surfaces include polymers, Braybrook et al., Prog. Polym. Sci. 15:715-734 (1990); metals, Stratmann, Adv. Mater. 2:191-195 (1990); silica, Bhatia et al., J. Am. Chem. Soc. 114:4432-4433 (1992); and graphite, Delamar, J. Am. Chem. Soc. 114:5883-5884 (1992). This research has been principally directed toward the development of novel composites, Baum et al., Chem. Mater. 3:714-720 (1991); resist materials, MacDonald et al., Chem. Mater. 3:435-442 (1991); biosensors, Pantano et al., J. Am. Chem. Soc. 113:1832-1833 (1991); and biomaterials, Allcock et al., Chem. Mater. 3:450-454 (1991). Recently, surface modification has been combined with photolithography to spatially direct the synthesis of peptides or oligonucleotides, Fodor et al., Science 251:767-773 (1991) and Kiederowski, Angew. Chem. Int. Ed. Eng. 30:822-823 (1991); and immobilization of biopolymers. Rozsnyai et al., Angew. Chem. Int. Ed. Enc. 31:759-761 (1992). Most of the surface modification processes known in the art involve sequential treatment of surfaces with chemical reagents. Id. Only a few such studies have involved the use of azides as surface-modification reagents. Breslow, in Scriven (ed.) Azides and Nitrenes, chapter 10, Academic Press, NY (1984); Harmer, Langmuir 7:2010-2012 (1991).
Examples of existing methods for modifying polymer films include sulfonation of polystyrene, Gibson et al., Macromolecules 13:34 (1980); sulfonation of poly(aryloxy)phosphazenes, Allcock et al., Chem. Mater. 3:1120 (1991); plasma treatment of polyester, Porta et al., Chem. Mater. 3:293 (1991); base hydrolysis of polyimide, Lee et al., Macromolecules 23:2097 (1990); base hydrolysis of polyphosphazenes, Allcock et al., Chem. Mater. 3:1441 (1991); and base treatment of poly(vinylidene fluoride), Dias et al., Macromolecules 17:2529 (1984).
Another conventional method for modifying polymers comprises exposing the surface of a hydrocarbon polymer such as polyethylene with nitrene or carbene intermediates generated in the gas phase. Breslow, in Scriven (ed.), Azides and Nitrenes, chapter 10, Academic Press, NY (1984). Also, difluorocarbene generated in solution has been reported to modify 1,4-polybutadienes. Siddiqui et al., Macromolecules 19:595 (1986).
Perfluorophenyl azides (PFPAs) have been shown to exhibit improved CH-insertion efficiency over their nonfluorinated analogues when the PFPAs were photolyzed in hydrocarbon solvents such as cyclohexane or toluene. Keana et al., Fluorine Chem. 43:151 (1989); Keana et al., J. Org. Chem. 55:3640 (1990); Leyva et al., J. Org. Chem. 54:5938 (1989); and Soundararajan et al., J. Org. Chem. 55:2034 (1990). PFPAs were initially developed as efficient photolabeling reagents. Cai et al., Bioconjugate Chem. 2:38 (1991); Pinney et al., J. Org. Chem. 56:3125 (1991); and Crocker et al., Bioconjugate Chem. 1:419 (1990). Recently, bis-(PFPA)s have been shown to be efficient cross-linking agents for polystyrene, Cai et al., Chem. Mater. 2:631 (1990); and poly(3-octylthiophene), Cai et al., J. Molec. Electron. 7:63 (1991).
In view of the present state of the art in chemical modification of surfaces, there remains a need for other methods for chemically functionalizing molecules on the surfaces of various materials, particularly in a single step.
There is also an ongoing need for new types of chemically modified molecules, particularly functionalized polymers, for use in any of a wide variety of applications.